1. Field of the Invention
The present invention relates to a mass spectrometer.
2. Discussion of the Prior Art
A common problem with known mass spectrometers is that the largest ions in a mass spectrum may originate from chemical species (i.e. background ions) which are of no interest to the analysis. For example, the background ions may comprise solvent ions, Gas Chromatograph carrier gas ions, Chemical Ionisation reagent gas ions or air peaks from vacuum leaks. These background ions can give rise to large ion signals which unless attenuated may saturate the ion detector thereby affecting the integrity of the mass spectra produced and reducing the lifetime of the ion detector.
It is therefore desired to provide an improved mass spectrometer.